484 



Mr DE morgan, ON THE SYLLOGISM, No. V. AND 



the new one is declared to be placed "alongside" of the old' one, we must needs infer — 

 unless the contrary be expressly stated — that both sets of forms are to be used in syl- 

 logism. If we be to have a thing so completely unheard of as a set of propositions which 

 have no syllogisms in which they combine, we feel that the writer will certainly give us warn- 

 ing of what we are not to expect: especially when the new system is to stand alongside 

 of the old one, side by side, in the same rank. Hamilton, writing on his own system, left a 

 rough but very elaborate sketch of propositional forms, and another of syllogisms {Lor/ic, ii. 

 277 — 28*, 2S5 — 289, appendixes (d) and (e)). These are given consecutively'' by his editors, 

 without a word indicating that it had passed through their minds that, of the two sets of 

 propositional forms given, the new one was, or might be, unconnected with the one system of 

 syllogism which appears to belong to both, for aught that Hamilton says to the contrary. 

 These volumes are edited, as was said of them in a review, " in the best style of laborious and 

 conscientious workmanship" : and they contain much more than a casual reader can appre- 

 ciate of unpretending reference and comparison. The additional papers, on which this discus- 

 sion arises, are put together in a manner which makes it clear that the trouble they cost 

 must have left the editors in close possession of their details. 



Finding that the new sense of " some" made syllogistic forms invalid, and having searched 

 in vain for anything even congruent with the notion that this new sense was not to be used 

 in syllogism, I publicly applied to Hamilton's followers for information. None was given for 

 a year. The editors' and Mr Baynes, who was Hamilton's substitute during illness, remained 



' "Though it may not supersede" the other: not "must 

 not," nor "ought not to ;" but only "may not." The phrase 

 is no more than permissive to the old system to remain, if 

 others insist on it. That this was the leaning of Hamilton's 

 mind — nay more, that disapprobation accompanied the per- 

 mission—is evidenced, I think, throughout his discussion. For 

 instance, by his interpolation quoted in the body of the paper, 

 to his reprint of the letter in the Atheiueum journal : here he 

 says that '"as we shall see, two particulars in the affirmative 

 and negative forms, ought to infer each other". To this it 

 must be added that (ix. ii. 234) he, in January 1830, demands 

 it as a postulate of Logic that " tlie some, if not otherwise qua- 

 lified, means some only — this by presumption." If we accept 

 Jir Baynes's statement, that some only (= some at most) was 

 not intended to be introduced into syllogism, and if some, with- 

 out qualification, be to mean some only, it follows that there 

 is to be no formal syllogism in which the quantifying word 

 ' some' stands alone. That the old forms can be well spared, 

 is clearly in Hamilton's meaning : and if tliey go, what have 

 we left ? Tlie new forths, without any syllogism? 



' It weighed much with me that one of the editors, Jlr 

 Mansel (iv. 113) came to his task with the conviction that 

 Hamilton had a use of "some" difi'erentfrom that of Aristotle; 

 and that tliis new sense of *' some" was applied to some sort of 

 syllogism. The quotation given in the l)ody of the paper 

 shows this. When the unpublished papers came into Mr 

 Mansel's hands, he, without any editorial remark, allowed the 

 syllogisms in appendix {e) to follow the new and additional 

 sen^^e of ' some' propounded in appendix (rf). I took it that 

 he — who had shown his belief tliat Hamilton did apply some 

 new 'some' to syllogism — had no reason to doubt that the 



syllogisms which he presented as editor were those which he 

 had opposed to mine as reviewer. I divided the responsibility 

 between Hamilton and the editors in the following words 

 {Aug. 17, liifil) — "I do not say that Hamilton himself would 

 have admitted this syllogism. But I do say that those who 

 will accept his writings as they stand must admit it." Mr 

 Mansel did not impeach either my interpretation of Hamilton, 

 or my implied interpretation of his own editorial proceeding. 

 I consequently became fixed in the belief, which I still hold, 

 that I had construed the editors rightly : and I believe that 

 they were right as well as I. Though they had examined («), 

 which it was not their business to do, with reference to the 

 validity of the connexion, they would not have been jus- 

 tified in deviating from the course they have taken. They 

 might have taken up my suspicion that Hamilton forgot, 

 after his seizure, that he had not finished his investigation. 

 They might have suggested what Mr Baynes asserts, but re- 

 fuses to prove in time for this paper, that the new propositions 

 were never intended to walk the world in pairs. But, whatever 

 they might have thought, it would have been their duty to put 

 the new syllogisms into tliat connexion with the new proposi- 

 tions which the state of the papers seemed to require ; leaving 

 their caveat, if they had given one, to work its own eft'ect on 

 the reader's judgment. 



' Mr Mansel, and Professor Fraser, Hamilton's successor, 

 have a right to the statement that they privately, in reply to 

 applications from me, made after my letters were published, 

 informed me that they had no more means of information than 

 were open to myself in print. It was not for me to ask what 

 opinion they had formed from these materials. The reader 

 will understand that the second public application, especially 



